Method for controlling variations of al-ti-c alloy grain refinement ability through controlling compression ratio

ABSTRACT

A method for controlling variations of Al—Ti—C alloy crystal grain refinement ability through controlling a compression ratio of sectional area of Al—Ti—C alloy including: A. establishing a relationship between variations of refinement ability of Al—Ti—C alloy crystal grain and parameters of press process of the Al—Ti—C alloy; setting the parameters of press process and controlling the variation of the refinement ability of the Al—Ti—C alloy crystal grain through controlling a value of the compression ratio.

The present invention relates to processing techniques, especiallyrelates to a method for controlling variations ofAl(aluminum)-Ti(titanium)-C(carbon) alloy crystal grain refinementthrough controlling a ratio of sectional area of Al—Ti—C alloy beforepress processing to after press processing (namely compression ratio)during a production of the Al—Ti—C alloy.

GENERAL BACKGROUND

Currently, Al—Ti—C alloy is much popularly employing in Al materialmachining as a most efficient preliminary alloy for Al and Al alloycoagulation crystal grain refinement. A refinement ability of theAl—Ti—C alloy crystal grain is a very important factor when judging aquality of Al processing material. Usually, the better the Al—Ti—C alloycrystal grain refinement ability is, the higher yield strength and thebetter malleability of the Al material are. Therefore, the Al—Ti—C alloymanufacturers and research organizations are forward into developingimprovements of the Al—Ti—C alloy crystal grain refinement ability. TheUS aluminum association has specially ruled an AA value to represent thecrystal grain refinement ability. The AA value is a value that can beused for measuring the Al—Ti—C alloy crystal grain refinement ability,and the lesser the AA value is, the better the refinement ability of theAl—Ti—C alloy is. That is, the lesser AA value that the Al—Ti—C alloyadded during Al and Al alloy producing process has, the more refined thecrystal grain of the Al and Al alloy are. With a development of theprocess and refinement technology, the AA value is decreased from 250 atvery beginning to 170. Presently, alloy fabrication technology isfocused on material components, melting process, and such like. However,a quality control during a press process of the Al—Ti—C alloy has beenignored or indifferent to people. The press process includes millrolling and cast extrusion machine extruding, and many believe that aratio of the sectional area before press process to that after pressprocess (defined as compression ratio), a variation of temperaturesbefore and after press process, a line speed at exit, and a quantity ofthe standers have relations with the refinement ability of the Al—Ti—Calloy crystal grain, and there is no quantitative optimal control methodfor control the refinement ability of the Al—Ti—C alloy crystal grainthrough these respects including compression ratio.

What is needed, therefore, is a method for controlling variations ofAl—Ti—C alloy crystal grain refinement ability through controlling acompression ratio of sectional area of Al—Ti—C alloy that can overcomethe above-described deficiencies.

SUMMARY

It is an object of the present invention to provide a method forcontrolling variations of Al—Ti—C alloy crystal grain refinement abilitythrough controlling a compression ratio of sectional area of Al—Ti—Calloy.

One exemplary embodiment of the present invention is a method forcontrolling variations of Al—Ti—C alloy crystal grain refinement abilitythrough controlling a compression ratio of sectional area of Al—Ti—Calloy including: A. establishing a relationship between variations ofrefinement ability of Al—Ti—C alloy crystal grain and parameters ofpress process of the Al—Ti—C alloy; setting the parameters of pressprocess and controlling the variation of the refinement ability of theAl—Ti—C alloy crystal grain through controlling a value of thecompression ratio.

Other novel features and advantages will become more apparent from thefollowing detailed description when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the drawings are not necessarily drawn to scale, theemphasis instead being placed upon clearly illustrating the principlesof at least one embodiment of the present invention. In the drawings,like reference numerals designate corresponding parts throughout variousviews, and all the views are schematic.

FIG. 1 is a schematic view of continuous casting and tandem rollingmanufacturing process employing a method for controlling variations ofAl—Ti—C alloy crystal grain refinement ability through controlling acompression ratio of sectional area of Al—Ti—C alloy according to anexemplary embodiment of the present invention.

FIG. 2 is a schematic view of continuous casting and continuousextruding manufacturing process employing the method for controllingvariations of Al—Ti—C alloy crystal grain refinement ability throughcontrolling a compression ratio of sectional area of Al—Ti—C alloy.

FIG. 3 is a schematic, plane structural view of part of a rolling millused for the method for controlling variations of Al—Ti—C alloy crystalgrain refinement ability through controlling a compression ratio ofsectional area of Al—Ti—C alloy.

FIG. 4 is a schematic, plane structural view of a cast extrusion machineused for the method for controlling variations of Al—Ti—C alloy crystalgrain refinement ability through controlling a compression ratio ofsectional area of Al—Ti—C alloy.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made to the drawings to describe preferred andexemplary embodiments in detail.

It has been proved that during a press process of the Al—Ti—C alloy, apressure parameter of the press process is directly related with therefinement ability of the Al—Ti—C alloy crystal grain by experimentsconducted by inventors of the present application using continuouscasting and tandem rolling machines, and continuous casting andcontinuous extruding machines. The pressure parameter is closelyrelevant to the refinement ability of the Al—Ti—C alloy crystal grain.The following is a table 1 showing part of the experiments data.

TABLE 1 S₁ (mm²) S₂ (mm²) $D = \frac{S_{1}}{S_{2}}$ ΔT (° C.) V (m/s) nΔ AA AA₁ AA₂  760 70.8 10.7 3 3 7 7.9 170 162  780 70.8 11.0 3 3 7 8.1170 162  800 70.8 11.3 3 3 7 8.3 170 162  960 70.8 13.6 3 3 7 9.9 170160  980 70.8 13.8 3 3 7 10.1 170 160 1000 70.8 14.1 3 3 7 10.4 170 1601160 70.8 16.4 3 3 7 12.0 170 158 1180 70.8 16.7 3 3 7 12.2 170 158 120070.8 16.9 3 3 7 12.4 170 158  760 70.8 10.7 4 6 8 10.3 170 160  780 70.811.0 4 6 8 10.6 170 159  800 70.8 11.3 4 6 8 10.9 170 159  960 70.8 13.64 6 8 13.0 170 157  980 70.8 13.8 4 6 8 13.3 170 157 1000 70.8 14.1 4 68 13.6 170 156 1160 70.8 16.4 4 6 8 15.8 170 154 1180 70.8 16.7 4 6 816.0 170 154 1200 70.8 16.9 4 6 8 16.3 170 154  760 70.8 10.7 5 9 10 9.9170 160  780 70.8 11.0 5 9 10 10.2 170 160  800 70.8 11.3 5 9 10 10.4170 160  960 70.8 13.6 5 9 10 12.5 170 157  980 70.8 13.8 5 9 10 12.8170 157 1000 70.8 14.1 5 9 10 13.0 170 157 1160 70.8 16.4 5 9 10 15.1170 155 1180 70.8 16.7 5 9 10 15.4 170 155 1200 70.8 16.9 5 9 10 15.7170 154

There is an international standard for the Al—Ti—C alloy production thatthe final product of the Al—Ti—C alloy should have a diameter of 9.5 mm,that is a sectional area of 70.8 mm². Contents of table 1 is part ofexperiments data conducted by continuous casting and tandem rollingmachines using a method for controlling variations of Al—Ti—C alloycrystal grain refinement ability through controlling a compression ratioof sectional area of Al—Ti—C alloy according to an exemplary embodimentof the present invention. The continuous casting and tandem rollingmachines includes a rolling mill 30 and a cooling module for Al—Ti—Calloy during a cooling press process. The cooling module includes atemperature sensor for detecting a temperature before the press processof the Al—Ti—C alloy and a temperature after the press process of theAl—Ti—C alloy. The press process of the Al—Ti—C alloy is completedthrough a cooperation of two rollers 31 of the rolling mill 30, and theAl—Ti—C alloy maintains solid state before, after, and during the pressprocess. During the press process, there are two points of temperaturesthat one point of the temperature is before the pressure being imposedand the other point of the temperature is after the pressure beingreleased. Before the pressure being imposed, an instantaneoustemperature of the Al—Ti—C alloy is about the same as an inputtemperature, and after the pressure being released, an instantaneoustemperature of Al—Ti—C alloy is about the same as an output temperature,therefore it is convenient to detect temperatures of the two points.

Referring to FIG. 1, Al—Ti—C alloy melt is put into a crystallize wheel20 from a crucible 10 thereby forming an Al—Ti—C alloy bar. Thereafter,the bar-shaped Al—Ti—C alloy is put into the rolling mill 30 to conductpress process. An amount of standers of the rolling mill 30 could be 3,4, 5, 6, 7, 8, 9 or 10. In the illustrated embodiment as shown in FIG.1, an amount of standers of the rolling mill 30 is 10. Referring to FIG.3, one stand of the rolling mill 30 is shown in enlarged view. The tworollers 31 of the rolling mill 30 are rolling inward and toward eachother. S₁ is denoted for the sectional area before press process, and S₂is denoted for the sectional area after the press process. There are atleast two temperature sensors provided therein, which are configured todetect the temperature of the Al—Ti—C alloy before the press process andthe temperature of the Al—Ti—C alloy after the press process. A scope oftemperatures of the Al—Ti—C alloy before the press process is between300° C.-450° C. The temperature of the Al—Ti—C alloy is raised whenbeing processed in the rolling mill 30. The cooling module is configuredfor spraying cooling fluid 50 onto the rollers 31 of the rolling mill30. By controlling a flow rate of the cooling fluid 50, a temperaturedifference ΔT of the Al—Ti—C alloy before the press process and afterthe press process can be controlled within a proper range. In theillustrated embodiment, the cooling fluid 50 can be water. The Al—Ti—Calloy comes out from the rolling mill 30 and forms an Al—Ti—C alloy rod.

From the data shown in table 1, the relation between the parameters ofthe press process and the refinement ability variation ΔAA can beconclude as the formula described below:

ΔAA=K·D·V/(ΔT·n)

In the formula, ΔAA=AA₁−AA₂, wherein AA₁ represents a refinement abilityvalue of the Al—Ti—C alloy before the press process, AA₂ represents arefinement ability value of the Al—Ti—C alloy after the press process. Kis a constant and can be calculated according the data of table 1 to be5.13. D represents the compression ratio, and D=S₁/S₂, S₁ is denoted forthe sectional area before press process, and S₂ is denoted for thesectional area after the press process. AT represents a temperaturevariation of the Al—Ti—C alloy before the press process and after thepress process. V represents a line speed of the outlet, and V=3ΔT−6, V≧1m/s. Currently the line speed V can reach high to 30 m/s. N representsthe number of the standers of the rolling mill 30.

The above-mentioned formula ΔAA=K·D·V/(ΔT·n) is applicable to bothsingle stander and a plurality of standers, that is, whether thecomputation is for total standers or for single stander, the formula isapplicable. When n=1, the computation means for the last one of thestanders, and the sectional area of the Al—Ti—C alloy products outputfrom the last stander is 70.8 mm².

In the production of the Al—Ti-c alloy, the press process parametersincluding temperature variation ΔT, line speed of the outlet V, and theamount of the standers are normally fixed, and through controlling onthe compression ratio of the press process of the Al—Ti—C alloy, therefinement ability variation ΔAA can be controlled precisely. As shownin table 1, when ΔT=4° C., V=6 m/s, and n=8, by controlling thecompression ratio D from 10.7 to 16.9, the refinement ability ΔAA canraised from 10.3 up to 16.3, and when the AA₁ value maintains at 170,the AA₂ value can be changed from 160 to 154.

TABLE 2 S₁ (mm²) S₂ (mm²) $D = \frac{S_{1}}{S_{2}}$ ΔT (° C.) V (m/s) nΔ AA AA₁ AA₂ 760 70.8 10.7 149 3 1 1.1 170 169 780 70.8 11.0 149 3 1 1.1170 169 800 70.8 11.3 149 3 1 1.2 170 169 960 70.8 13.6 149 3 1 1.4 170169 980 70.8 13.8 149 3 1 1.4 170 169 1000 70.8 14.1 149 3 1 1.5 170 1691160 70.8 16.4 149 3 1 1.7 170 168 1180 70.8 16.7 149 3 1 1.7 170 1681200 70.8 16.9 149 3 1 1.8 170 168 1360 70.8 19.2 149 3 1 2.0 170 1681380 70.8 19.5 149 3 1 2.0 170 168 1400 70.8 19.8 149 3 1 2.0 170 168760 70.8 10.7 150 4 1 1.5 170 169 780 70.8 11.0 150 4 1 1.5 170 168 80070.8 11.3 150 4 1 1.5 170 168 960 70.8 13.6 150 4 1 1.9 170 168 980 70.813.8 150 4 1 1.9 170 168 1000 70.8 14.1 150 4 1 1.9 170 168 1160 70.816.4 150 4 1 2.2 170 168 1180 70.8 16.7 150 4 1 2.3 170 168 1200 70.816.9 150 4 1 2.3 170 168 1360 70.8 19.2 150 4 1 2.6 170 167 1380 70.819.5 150 4 1 2.7 170 167 1400 70.8 19.8 150 4 1 2.7 170 167 760 70.810.7 149 5 1 1.8 170 168 780 70.8 11.0 149 5 1 1.9 170 168 800 70.8 11.3149 5 1 1.9 170 168 960 70.8 13.6 149 5 1 2.3 170 168 980 70.8 13.8 1495 1 2.4 170 168 1000 70.8 14.1 149 5 1 2.4 170 168 1160 70.8 16.4 149 51 2.8 170 167 1180 70.8 16.7 149 5 1 2.9 170 167 1200 70.8 16.9 149 5 12.9 170 167 1360 70.8 19.2 149 5 1 3.3 170 167 1380 70.8 19.5 149 5 13.4 170 167 1400 70.8 19.8 149 5 1 3.4 170 167 760 70.8 10.7 151 6 1 2.2170 168 780 70.8 11.0 151 6 1 2.2 170 168 800 70.8 11.3 151 6 1 2.3 170168 960 70.8 13.6 151 6 1 2.8 170 167 980 70.8 13.8 151 6 1 2.8 170 1671000 70.8 14.1 151 6 1 2.9 170 167 1160 70.8 16.4 151 6 1 3.3 170 1671180 70.8 16.7 151 6 1 3.4 170 167 1200 70.8 16.9 151 6 1 3.5 170 1671360 70.8 19.2 151 6 1 3.9 170 166 1380 70.8 19.5 151 6 1 4.0 170 1661400 70.8 19.8 151 6 1 4.0 170 166

Contents of table 2 is part of experiments data conducted by continuouscasting and continuous extruding machines designed by the applicant andusing a method for controlling variations of Al—Ti—C alloy crystal grainrefinement ability through controlling a compression ratio of sectionalarea of Al—Ti—C alloy according to an exemplary embodiment of thepresent invention. The continuous casting and continuous extrudingmachines includes a casting extrusion machine 40 and a cooling modulefor Al—Ti—C alloy during a cooling press process. The press process ofthe Al—Ti—C alloy is competed in a roller of the casting extrusionmachine 40. The Al—Ti—C alloy maintains solid state before, after, andduring the press process. During the press process, there are two pointsof temperatures that one point of the temperature is before the pressurebeing imposed and the other point of the temperature is after thepressure being released. Before the pressure being imposed, aninstantaneous temperature of the Al—Ti—C alloy is about the same as anfriction heat temperature, and after the pressure being released, aninstantaneous temperature of Al—Ti—C alloy is about the same as antemperature outputted from the casting extrusion machine 40, thereforeit is convenient to detect temperatures of the two points.

Referring to FIG. 2, Al—Ti—C alloy melt is put into a crystallize wheel20 from a crucible 10 thereby forming an Al—Ti—C alloy bar. Thereafter,the bar-shaped Al—Ti—C alloy is put into the casting extrusion machine40 to conduct press process.

Referring to FIG. 2, Al—Ti—C alloy melt is put into a crystallize wheel20 from a crucible 10 thereby forming an Al—Ti—C alloy bar. Thereafter,the bar-shaped Al—Ti—C alloy is put into the casting extrusion machine40 to conduct press process. An amount of the standers of the castingextrusion machine 40 is as shown in FIG. 2. Referring to FIG. 4, S₁ isdenoted for the sectional area before press process, and S₂ is denotedfor the sectional area after the press process. There are at least twotemperature sensors provided therein, which are configured to detect thetemperature of the Al—Ti—C alloy before the press process and thetemperature of the Al—Ti—C alloy after the press process. Thetemperature of the Al—Ti—C alloy is raised when being processed in thecasting extrusion machine 40 and the Al—Ti—C alloy is altered intosemifluid. The cooling module spraying cooling fluid into the castingextrusion machine 40. By controlling a flow rate of the cooling fluid, atemperature difference ΔT of the Al—Ti—C alloy before the press processand after the press process can be controlled within a proper range. Inthe illustrated embodiment, the cooling fluid can be water. The Al—Ti—Calloy comes out from the casting extrusion machine 40 and forms anAl—Ti—C alloy rod.

From the data shown in table 1, the relation between the parameters ofthe press process and the refinement ability variation ΔAA can beconclude as the formula described below:

ΔAA=K·D·V/(ΔT·n)

In the formula, ΔAA=AA₁−AA₂, wherein AA₁ represents a refinement abilityvalue of the Al—Ti—C alloy before the press process, AA₂ represents arefinement ability value of the Al—Ti—C alloy after the press process. Kis a constant and can be calculated according the data of table 1 to be5.13. D represents the compression ratio, and D=S₁/S₂, S₁ is denoted forthe sectional area before press process, and S₂ is denoted for thesectional area after the press process. ΔT represents a temperaturevariation of the Al—Ti—C alloy before the press process and after thepress process. V represents a line speed of the outlet. N represents thenumber of the standers of the casting extrusion machine 40, and n=1.

The above-mentioned formula ΔAA=K·D·V/(ΔT·n) is applicable to castingextrusion machine 40 with single stander. When n=1, the computationmeans for the last one of the standers, and the sectional area of theAl—Ti—C alloy products output from the last stander is 70.8 mm².

In the production of the Al—Ti-c alloy, the press process parametersincluding temperature variation ΔT, line speed of the outlet V, and theamount of the standers are normally fixed, and through controlling onthe compression ratio of the press process of the Al—Ti—C alloy, therefinement ability variation ΔAA can be controlled precisely. As shownin table 2, when ΔT=150° C., V=4 m/s, and n=1, by controlling thecompression ratio D from 10.7 to 19.8, the refinement ability ΔAA canraised from 1.5 to 2.7, and when the AA₁ value maintains at 170, the AA₂value can be changed from 169 to 167.

The method for controlling variations of Al—Ti—C alloy crystal grainrefinement ability through controlling a compression ratio of sectionalarea of Al—Ti—C alloy has overcome the deficiencies of conventionaltechnique for Al—Ti—C alloy process, and proved that variations of therefinement ability can be controlled through controlling a compressionratio of sectional area of Al—Ti—C alloy. By adopting the presentinvention, with the parameters of press process, the temperaturevariation before and after the press process, the line speed of outlet,and the amount of the standers being set fixed, the variations of therefinement ability of Al—Ti—C alloy crystal grain can be preciselycontrolled by controlling the compression ratio. The greater thevariation is, the better the refinement ability of Al—Ti—C alloy crystalgrain is with a certain AA value before the press process and a lesserAA value after the press process.

It is to be understood, however, that even though numerouscharacteristics and advantages of exemplary and preferred embodimentshave been set out in the foregoing description, together with details ofthe structures and functions of the embodiments, the disclosure isillustrative only, and changes may be made in detail, especially inmatters of shape, size, and arrangement of parts within the principlesof the invention to the full extent indicated by the broad generalmeaning of the terms in which the appended claims are expressed.

1. A method for controlling variations of Al—Ti—C alloy crystal grainrefinement ability through controlling a compression ratio of sectionalarea of Al—Ti—C alloy comprising: a. establishing a relationship betweenvariations of refinement ability of Al—Ti—C alloy crystal grain andparameters of press process of the Al—Ti—C alloy:ΔAA=K·D·V/(ΔT·n) wherein ΔAA=AA₁−AA₂, AA₁ represents a refinementability value of the Al—Ti—C alloy before the press process, AA₂representing a refinement ability value of the Al—Ti—C alloy after thepress process, K being a constant, wherein D=S₁/S₂,S₁ being denoted forthe sectional area before press process, and S₂ being denoted for thesectional area after the press process, wherein ΔT represents atemperature variation of the Al—Ti—C alloy before the press process andafter the press process, V representing a line speed of an outlet, nrepresenting a number of the standers of process machine; and b. settingthe parameters V, ΔT, and n, and controlling the ΔAA value throughcontrolling a value of the compression ratio D.